The inventor is unaware of any pertinent prior art that is available. U.S. Pat. No. 5,435,293 issued to Grimaldi on Jul. 25, 1995 discloses a device that will encourage a shooter to develop binocular vision. The device of Grimaldi uses a plate that is placed between the shooter's eyes to limit the field of vision to one side of the plate or the other. This forces the shooter to use both eyes instead of using one dominate eye. The instant invention will block the vision in one eye allowing the user to leave both eyes open during the sighting phase of shooting. This blocking of the other eye or non-dominate eye prevents a condition of double vision from occurring. This is the essence of the invention, that is, the blocker prevents double vision by blocking the second eye from viewing the target but still allows that eye to be open.